1. Field of the Invention
The present invention relates to an electronic camera which converts the light from an object into electrical image signals to record them on a recording medium.
2. Related Background Art
The structure of a conventional electronic camera is shown in FIG. 6. The conventional electronic camera 61 comprises a zoom lens 62 which is an image magnification variable taking lens, an optical zoom finder 3 of a variable enlarging magnification type, an image sensor 4 to receive the light rays from an object and convert them into electrical image signals, a recording medium 6 to record the foregoing image signals, a metering device 7 to measure the distance between the object and the camera, a zooming lever 8 to vary the image magnification of the zoom lens 62 and the enlarging magnification of the zoom finder 3, and a control device 5. In FIG. 6, reference numeral 10 designates an object and 11 designates a photographer.
The conventional electronic camera 61 thus structured performs its photographing operations set forth below. The photographer 11 observes the object 10 through the zoom finder to operate the zooming lever 8 to set a desired image magnification. When the zooming lever 8 is held down to the left in FIG. 6, a switch SW1 is turned on. The zoom finder 3 is driven by a driving device which is not shown to shift a member 3a of its optical system thereby to enlarge the object image in a given frame of a field. Hence, the enlarging magnification is increased. A member 62a of the optical system in the zoom lens 62 is interlocked with the zooming operation of the foregoing finder 3. It is thus shifted to cause its image magnification to be increased in proportion to the image magnification of the zoom finder 3. The size of the object image occupying the light receiving area of the image sensor 4 is increased accordingly.
When the zooming lever 8 is held down to the right in FIG. 6, a switch SW2 is turned on. The zoom finder is driven by a driving device which is not shown to shift member 3a of its optical system in the direction opposite to the foregoing operation thereby to reduce the enlarging magnification of the zoom finder 3. At the same time, the member 62a of the optical system in the zoom lens 62 is interlocked with this operation. It is thus shifted to decrease its image magnification in proportion to the image magnification of the zoom finder 3.
As described above, the operation is performed so that the ratio between the object image observed by the photographer 11 through the finder 3 and the field frame, and the ratio between the object image projected on the image sensor 4 and the light receiving area of the image sensor can be equal.
Then, when the photographer depresses a release button (not shown), a metering device 7 is caused to measure the distance between the camera and the object. A member of the optical system of the zoom lens 62 is driven by a driving device which is not shown in accordance with such a measured value to allow the object image to be imaged on the image sensor 4. Thus, the image information on the foregoing image sensor 4 is recorded on a recording medium 6.
FIG. 7 and FIGS. 8A and 8B are views showing another example of the prior art. As shown in FIG. 7, an electronic camera 71 comprises a taking lens 72, a finder CRT 73, an image sensor 4, a control device 5, a recording medium 6, a metering device 7, a zooming lever 8, and an image memory 9. A reference numeral 10 designates an object, and 11 designates a photographer. FIG. 8A illustrates an image displayed on the finder CRT. FIG. 8B illustrates an image formed on the image sensor 4. Here, the image B formed on the image sensor is reversed due to the optical effect of the taking lens.
In the photographing operation of this electronic camera, when the photographer turns on a power source of the camera by a power source switch which is not shown, the distance between the camera and the object is measured by the metering device 7. Then, in accordance with the metered information, a member 72b of the optical system of the taking lens 72 is driven by a driving device which is not shown to enable the object image to be focused on the image sensor 4. The image sensor 4 converts the optical information into electrical signals to record them in the image memory 9. The signals inputted into the image memory 9 are read to be displayed on the finder CRT 73.
The photographer 11 observes the object image displayed on the finder CRT 73 and operates the zooming lever 8 to set a desired photographing magnification. When this zooming lever 8 is held down to the left in FIG. 7, a switch SW1 is turned on, and while referring to the images shown in FIGS. 8A and 8B, an area C in the image B formed on the image sensor 4 is enlarged by the image memory. This enlarged image is displayed on the finder CRT 73. Then, the foregoing area C is further narrowed by the operation of the zooming lever 8. Thus, it is possible to increase the enlarging magnification still more.
When the zooming lever 8 is held down to the right in FIG. 7, a switch SW2 is turned on. Then, the area C shown in FIG. 8B is enlarged to an area designated by a reference mark B. The photographing magnification becomes small, and this image is displayed on the finder CRT 73.
This electronic camera 71 according to the prior art is capable of varying the enlarging magnification of an object electrically with the operations described above, and when a release button which is not shown is depressed, the control device 5 is driven to record the image displayed on the finder CRT 73 in the recording medium 6.
In the conventional electronic cameras described above, problems are encountered as set forth below. In the electronic camera 61 shown in FIG. 6, it is required to mechanically interlock and drive the two optical members having different shifting distance, namely, the optical member 62a in the zoom lens 62 and the optical member 3a in the zoom finder 3. Thus, there is a problem that the mechanism of the camera becomes inevitably complicated.
Furthermore, if the photographing magnification is great and the distance to an object is short, so-called parallax occurs. This is a phenomenon whereby a deviation takes place between an object visualized in a finder and the actual object to be photographed. This phenomenon is caused by a deviation between the optical center of a zoom lens and the optical center of a zoom finder.
With reference to FIG. 6 this phenomenon will be described. As shown in FIG. 6, there is an object 10 on the extension of the optical axis P1 of the zoom finder 3. Therefore, the object 10 is observed in the center of the zoom finder 3. However, since no object is present on the optical axis Q of the zoom lens 62, the object 10 is not imaged in the center of the image sensor 4 but is imaged in a position away from the center of the image sensor by a distance x. As a result, any image taken by this camera 61 differs from the image desired by the photographer 11 when visualized through the finder 3.
In the conventional electronic camera shown in FIG. 7, there is no need for the two optical members, the zoom lens and zoom finder, to be interlocked as in FIG. 6. Also, no deviation takes place between the optical axis of the finder and the optical axis of the taking lens. There is no possibility that any parallax is generated at all.
However, in the foregoing electronic camera, the finder CRT 73 and image sensor 4 are constantly energized while the photographer 11 observes the finder 73. Consequently, it is necessary to provide a battery of a large capacity, not only making it necessary to make the camera large, but also increasing the manufacturing cost of the camera due to the provision of the aforesaid CRT 73.